1. Field of the Invention
The present invention relates to an automatic water drain system, for use with a gas system, which allows for the automatic removal of water from gas lines and sediment traps, without relying on manual drainage or sensitive floatation devices for non-manual removal, and is suitable for use generally with a gas digester system and, in particular, a sediment trap.
2. Description of the Related Art
The typical method or apparatus for removing condensed water from gas lines in a gas digester system is to run gas lines through sediment traps, which are well known in the art. These sediment traps usually consist of a cylindrical tank or enclosed chamber and are of sufficient volume to store a substantial volume of water and sediment. Digester gas is rather wet and this moisture condenses as the digester gas travels from the heated tank to a cooler temperature. As gas runs through the gas lines and into the sediment trap, condensed water and sediment separates from the gas and collects at the bottom of the sediment trap. At some time, however, these sediment traps will become full and require draining. Since a larger volume of water is produced than sediment, the water requires draining more frequently. Thus, simply attaching a drain at the bottom of the sediment trap may not be practical in that sediment will be drained along with water every time the trap is drained.
To address the problem of how to drain water but not sediment, "drip traps" have been developed and used. The typical drip trap is an enclosed chamber configured to fit externally at the bottom of the sediment trap and receive water, but not sediment, as water collects in the sediment trap (these drip traps usually hold a liter or two of water). The drip trap, then, is drained thereby draining only water from the sediment trap. One such device is an enclosed chamber without an output port that can be manually opened and closed with a manually operated valve to release the accumulated water. These drip traps generally must be drained at least once a day, and possibly more frequently in cooler weather. One problem that exists with drip traps of the manual operation type, is that they require manual effort to be drained and operate effectively. Thus, they rely on the human factor. Such traps, therefore, are prone to neglect insofar as individuals may forget or neglect to drain the devices. If the drip traps are not drained, the excess water will accumulate in the sediment trap and eventually spill over into the gas pipes which could cause damage to compressors, boilers and blowers as well as interfere with gas utilization. Another such device is also referred to as an automatic drip trap and is equipped with a float and needle valve orifice. The device operates by "automatically" draining when the water column in the drip trap rises, thereby raising the float, which in turn, opens the valve to the trap and releases water. The problem with such devices is that corrosion, sediment, or scale in the gas system can and does prevent the needle from seating or shutting completely after drainage. This, in turn, causes the drip trap to leak water. When the leak has caused all of the water in the sediment trap to drain, gas will then leak into the atmosphere. This has very dangerous and deleterious effects on the health of people in the vicinity as well as the environment. In addition, both types of devices are expensive, requiring precisely machined drip traps for effective use and extensive maintenance for manual drainage, repairing leaking valves or repairing equipment down the gas stream damaged by water that spilled over into the gas lines.
Hence there is a need for a device that provides automatic drainage yet is reliable, inexpensive and requires little maintenance.